Stop narrating rollup buckets the record cannot account for

A rollup band outlives the rows it was folded from. The read-swap falls back to
live SQL only when a band is EMPTY, so a bucket that is merely wrong is served
as current; `ensureUserRollupsFresh` repairs the DAY tier over the trailing 90
days only, and keys off `Measurement.updatedAt`, which a hard delete does not
bump. The WHOOP body sync hard-deletes a WEIGHT row with no invalidation, so a
MONTH bucket keeps reporting a value the record no longer holds.

The block was handing the model two irreconcilable accounts of the same record
and marking neither: the coarse tail said one thing, the all-time extremes read
live beside it said another, and `asOf` stamped the whole thing current because
it is derived from raw reading age and knows nothing about rollup age.

Reconcile them where they are assembled. A bucket mean is an average of real
rows, so it cannot fall outside those rows' own all-time extremes — when it
does, the band is describing readings the live read cannot see. That is an
invariant rather than a heuristic, so the disputed tail is dropped and
`asOf.coarseHistoryWithheld` records that it went. Narrating a ghost is worse
than narrating less.

`currentForTodayClaims` stays keyed to raw recency, which is what it means. The
surviving readings really are from today, and suppressing a true present-tense
statement to punish a stale history band would trade one dishonesty for another.

The bucket on disk is still wrong, and a wide event now says so. The deeper fix
is to make the tier notice — compare a bucket's `computedAt` against the type's
in-window MAX(`updatedAt`), or invalidate on the hard-delete path — which is a
larger change than this repair.

src/lib/ai/coach/snapshot-freshness.ts

@@ -16,6 +16,14 @@
  * directly, so the answer arrives with the data instead of depending on the
  * reader working it out.
  *
+ * The same pass reconciles each block's coarse (MONTH / YEAR) timeline, served
+ * from the rollup tier, against the all-time extremes read live beside it. The
+ * read-swap falls back to live SQL only when a band is EMPTY, so a bucket whose
+ * rows were hard-deleted with no invalidation keeps being served as current —
+ * and the block then states two different things about the same record with
+ * nothing saying which is right. A bucket mean cannot lie outside its own rows'
+ * extremes, so when it does the band is dropped rather than narrated.
+ *
  * Pure and in-place — the snapshot is a plain record by the time it gets here.
  */
 import {
@@ -35,6 +43,12 @@ export interface SnapshotAsOf {
    * the day they were taken on, and must be stated with that day.
    */
   currentForTodayClaims: boolean;
+  /**
+   * Set when the block's coarse (MONTH / YEAR) timeline was dropped because it
+   * could not be reconciled with the live record beside it. Present only in
+   * that case, so its absence is the normal state and costs no prompt budget.
+   */
+  coarseHistoryWithheld?: true;
 }
 
 function readNewestDaysAgo(block: unknown): number | null {
@@ -61,27 +75,117 @@ export function asOfFromDaysAgo(daysAgo: number): SnapshotAsOf {
   };
 }
 
+/** Coarse-band bucket rows are `[bucketStart, mean, min, max]`. */
+type CoarseBucket = [string, number, number, number];
+
+/** Rounding headroom, so a float artefact is never read as a contradiction. */
+const RECONCILE_EPSILON = 1e-6;
+
+function readAllTimeExtremes(
+  block: unknown,
+): { min: number; max: number } | null {
+  if (typeof block !== "object" || block === null) return null;
+  const aggregate = (block as { aggregate?: unknown }).aggregate;
+  if (typeof aggregate !== "object" || aggregate === null) return null;
+  const min = (aggregate as { allTimeMin?: unknown }).allTimeMin;
+  const max = (aggregate as { allTimeMax?: unknown }).allTimeMax;
+  if (typeof min !== "number" || !Number.isFinite(min)) return null;
+  if (typeof max !== "number" || !Number.isFinite(max)) return null;
+  return { min, max };
+}
+
+function readCoarse(block: unknown): Record<string, unknown> | null {
+  if (typeof block !== "object" || block === null) return null;
+  const timeline = (block as { timeline?: unknown }).timeline;
+  if (typeof timeline !== "object" || timeline === null) return null;
+  const coarse = (timeline as { coarse?: unknown }).coarse;
+  if (typeof coarse !== "object" || coarse === null) return null;
+  return coarse as Record<string, unknown>;
+}
+
+function bucketsOf(coarse: Record<string, unknown>, band: string): number[] {
+  const rows = coarse[band];
+  if (!Array.isArray(rows)) return [];
+  return (rows as CoarseBucket[])
+    .map((row) => (Array.isArray(row) ? row[1] : Number.NaN))
+    .filter((v): v is number => typeof v === "number" && Number.isFinite(v));
+}
+
+/**
+ * Decide whether a block's coarse timeline can be reconciled with the live
+ * record it sits beside.
+ *
+ * The coarse MONTH / YEAR bands are served from the rollup tier; the aggregate's
+ * all-time extremes are read live. A bucket mean is an average of real rows, so
+ * it MUST lie within the all-time min/max of those same rows. When it does not,
+ * the rollup is describing readings the live read cannot see — the bucket
+ * outlived the rows it was folded from.
+ *
+ * This is an invariant, not a heuristic: no arrangement of existing rows can
+ * average to a value outside their own extremes.
+ */
+function coarseContradictsRecord(block: unknown): boolean {
+  const extremes = readAllTimeExtremes(block);
+  if (extremes === null) return false;
+  const coarse = readCoarse(block);
+  if (coarse === null) return false;
+  const means = [
+    ...bucketsOf(coarse, "monthly"),
+    ...bucketsOf(coarse, "yearly"),
+  ];
+  if (means.length === 0) return false;
+  return means.some(
+    (mean) =>
+      mean < extremes.min - RECONCILE_EPSILON ||
+      mean > extremes.max + RECONCILE_EPSILON,
+  );
+}
+
 /**
  * Attach `asOf` to every snapshot block whose aggregate reports a freshest
  * reading. Blocks with no coverage (narrative memory, plans, the reference
  * grounding table) are untouched — they carry no measurement to date.
  *
- * Returns the metric keys that were stamped stale, so the caller can annotate
- * them: a briefing narrated off a week-old series is worth seeing in the wide
- * event, not just in the reader's confusion.
+ * Also drops a coarse timeline that contradicts the live record beside it. The
+ * rollup tier's read-swap falls back to live SQL only when a band is EMPTY, so
+ * a bucket that is merely WRONG — the rows behind it deleted, and no
+ * invalidation fired — is served as though it were current. The block then
+ * carried two irreconcilable accounts of the same record (a coarse tail saying
+ * one thing, all-time extremes saying another) with nothing marking which to
+ * believe, under an `asOf` stamped from raw reading age that knows nothing
+ * about rollup age. Narrating a ghost is worse than narrating less, so the
+ * disputed tail goes and `coarseHistoryWithheld` says it went.
+ *
+ * `currentForTodayClaims` stays keyed to raw recency, which is what it means:
+ * the freshest READING is still as fresh as it was, and suppressing it would
+ * silence a true present-tense statement to punish a stale history band.
+ *
+ * Returns the metric keys stamped stale and the keys whose coarse tail was
+ * withheld, so the caller can annotate both: a briefing narrated off a week-old
+ * series is worth seeing in the wide event, and so is a rollup that has drifted
+ * away from the rows underneath it.
  */
-export function annotateSnapshotFreshness(
-  snapshot: Record<string, unknown>,
-): string[] {
+export function annotateSnapshotFreshness(snapshot: Record<string, unknown>): {
+  stale: string[];
+  coarseWithheld: string[];
+} {
   const stale: string[] = [];
+  const coarseWithheld: string[] = [];
   for (const [key, block] of Object.entries(snapshot)) {
     const daysAgo = readNewestDaysAgo(block);
     if (daysAgo === null) continue;
     const asOf = asOfFromDaysAgo(daysAgo);
+    if (coarseContradictsRecord(block)) {
+      const timeline = (block as { timeline?: Record<string, unknown> })
+        .timeline;
+      if (timeline) delete timeline.coarse;
+      asOf.coarseHistoryWithheld = true;
+      coarseWithheld.push(key);
+    }
     (block as Record<string, unknown>).asOf = asOf;
     if (!asOf.currentForTodayClaims) stale.push(key);
   }
-  return stale;
+  return { stale, coarseWithheld };
 }
 
 export { TODAY_CLAIM_MAX_AGE_DAYS };

src/lib/ai/coach/snapshot.ts

@@ -1238,11 +1238,20 @@ async function buildCoachSnapshotImpl(
   // hero line said "today" about a metric last measured five days earlier. The
   // stamp sits on the block itself so the age travels with the numbers into
   // every surface the snapshot feeds — hero, briefing, Coach reply, tools.
-  const staleBlocks = annotateSnapshotFreshness(compactSnapshot);
-  if (staleBlocks.length > 0) {
+  const freshness = annotateSnapshotFreshness(compactSnapshot);
+  if (freshness.stale.length > 0) {
     annotate({
       action: { name: "coach.snapshot.stale_blocks" },
-      meta: { blocks: staleBlocks.sort() },
+      meta: { blocks: freshness.stale.sort() },
+    });
+  }
+  // A rollup band that no longer reconciles with the rows underneath it is an
+  // operator-visible defect, not just a narration problem — the bucket is wrong
+  // on disk and stays wrong until something recomputes it.
+  if (freshness.coarseWithheld.length > 0) {
+    annotate({
+      action: { name: "coach.snapshot.coarse_withheld" },
+      meta: { blocks: freshness.coarseWithheld.sort() },
     });
   }
 

src/lib/insights/__tests__/measurement-freshness.test.ts

@@ -119,9 +119,11 @@ describe("the Coach snapshot stamp", () => {
       scope: { sources: ["pulse", "weight"] },
     };
 
-    const stale = annotateSnapshotFreshness(snapshot);
+    const { stale, coarseWithheld } = annotateSnapshotFreshness(snapshot);
 
     expect(stale).toEqual(["pulse"]);
+    // Neither block carries a coarse band, so nothing is disputed.
+    expect(coarseWithheld).toEqual([]);
     expect((snapshot.pulse as { asOf: unknown }).asOf).toEqual({
       daysAgo: 5,
       isToday: false,
@@ -135,4 +137,63 @@ describe("the Coach snapshot stamp", () => {
     expect(snapshot.memory).toEqual({ headline: "steady month" });
     expect(snapshot.scope).toEqual({ sources: ["pulse", "weight"] });
   });
+
+  /**
+   * A coarse bucket mean is an average of real rows, so it cannot sit outside
+   * those rows' own all-time extremes. When it does, the rollup band is
+   * describing readings the live read cannot see and must not be narrated.
+   */
+  it("drops a coarse band whose bucket mean the live extremes cannot account for", () => {
+    const snapshot: Record<string, unknown> = {
+      weight: {
+        aggregate: {
+          allTimeMin: 80,
+          allTimeMax: 80,
+          coverage: { count: 6, newestDaysAgo: 0 },
+        },
+        timeline: {
+          recent: [],
+          coarse: { monthly: [["2026-01-01", 95, 95, 95]], yearly: [] },
+        },
+      },
+    };
+
+    const { coarseWithheld } = annotateSnapshotFreshness(snapshot);
+
+    expect(coarseWithheld).toEqual(["weight"]);
+    const weight = snapshot.weight as {
+      timeline: { coarse?: unknown };
+      asOf: { coarseHistoryWithheld?: true; currentForTodayClaims: boolean };
+    };
+    expect(weight.timeline.coarse).toBeUndefined();
+    expect(weight.asOf.coarseHistoryWithheld).toBe(true);
+    // Raw recency is untouched — the surviving readings are still from today.
+    expect(weight.asOf.currentForTodayClaims).toBe(true);
+  });
+
+  it("keeps a coarse band that reconciles with the live extremes", () => {
+    const snapshot: Record<string, unknown> = {
+      weight: {
+        aggregate: {
+          allTimeMin: 78,
+          allTimeMax: 96,
+          coverage: { count: 40, newestDaysAgo: 0 },
+        },
+        timeline: {
+          recent: [],
+          coarse: { monthly: [["2026-01-01", 95, 94, 96]], yearly: [] },
+        },
+      },
+    };
+
+    const { coarseWithheld } = annotateSnapshotFreshness(snapshot);
+
+    expect(coarseWithheld).toEqual([]);
+    const weight = snapshot.weight as {
+      timeline: { coarse?: unknown };
+      asOf: { coarseHistoryWithheld?: true };
+    };
+    expect(weight.timeline.coarse).toBeDefined();
+    expect(weight.asOf.coarseHistoryWithheld).toBeUndefined();
+  });
 });